Electrical oscillator.



F. K. VREELAND.

ELECTRICAL OSGILLATOB.

APPLIOATION FILED nno.15,19os.

Patented 061.2511910.

Witzie o UNITED sTATEs PATENT o-EEIcE.

FREDERICK K. VBEELAND, lOF MONTCLAIR, NEW JERSEY, ASSIGNOB T0 WIRELESS TELEGRAPH EXPLOITATION COMPANY, OF NEW YORK, N. Y., A CORPORATION OIEv NEW YORK.

ELECTRICAL OSCILLATOR.

Specification of Letters Patent.

Application led December 15, 1906.` Serial No. 348,085.

To all 'whom it ma/y concern:

Be it known that I, FREDERICK K. VREE- LAND, a citizen of the United States, residing at Montclair, in the county of Essex and State of New Jersey, have invented a certain new and useful Improvement in Electrical Oscillators, of which the following is a description.

My invention relates to electrical oscillators of the character described in my United States Patents Nos. 829,447 and 829,934 and involves the electrical commutation of energy in a gaseous medium, such as a mercury vapor tube, by means of a magnetic field excited or controlled by the oscillations of anelectrical oscillating circuit.

By my presentinvention I, utilize the fact that an axial magnetic field, i. e., a field whose direction is approximately parallel to the direction of the current in a gaseous medium, tends to concentrate the discharge and to guide it in the direction of the magnetic flux. This is particularly true of that portion of the discharge which emanates from the cathode and consists in negative electrons or corpuscles. An axial magnetic field concentrates this stream of negative elect-rens into an intense, brilliant beam or blast which emanates. from the cathode and flows approximately in the direction of the magnetic flux until it is `checked by impinging on the walls of the tube or some other obstacle; or further deflected by the preponderance of the electrical forces over the magnetic ones.` If the direction of the magnetic field is such as to concentrate the cathode blast on the anode the conductivity of the gas column is increased so that the voltage necessary to force a given current.

through the gas column is correspondingly diminished. If, on the other hand, the direct-ion of the field is such as to deflect the blast away from the anode the conductivity of the gas column is less than it would be if the field were entirely absent. These .facts are utilized in the invention herein described. l

In the accompanying drawing, in which forms of apparatus embodying the invention are illustrated largely in diagram, Figure 1 is a sectional view of one form 'of tube and its associated field coils; Fig. 2 is a diagram illustrating the connections of the apparatus .of Fig. 1; and Figs. 3, 4, 5, and 6 are views illustrating modified arrangements.

Referring to Figs. 1 and 2, 1 is a vacuum tube, preferably a mercury vapor tube, containing a single cathode 2 of mercury and two anodes 3, 4 of carbon, iron or other suitable material. Both anodes are preferably oblong and curved on an arc having its center at or near the cathode.

5 is a field coil whose axis coincides with the axis of the tube and whose flux tends to concentrate the cathode blast in a direction midway between the two anodes.

6 is another field coil (or coils) whose axis is perpendicular to that of the coil 5, and is located in a vertical plane passing through both anodes 3, 4. The direction of the field of coil 5 is represented by the arrow a, and the direction'of the field of coil 6 (which is an alternating one) is represented by the horizontal arrows I), b. l/Vhen the current in the coil 6 is, say, in -the positive direction, and its field is represented by thef arrow Z), the resultant magnetic flux o deflects the cathode blast from its normal direction a toward the anode 3. Hence, the conductivty of the path 3, 2 is greater than that of the path 4, 2, and the current will fiow more readily through the former path. When the current in the field coil 6 is negative its magnetomotive force is in the direction b', and the resultant fiux c will concentrate the blast on the anode 4, which in its turn will carry the larger current. This concentration and deflection of the cathode blast is utilized to excite electrical oscillations by means of the arrangement of connections shown in Fig. 2. 7 is a battery or source of electrical current, the negative terminal of which is connected to the cathode 2 of the tube 1, and the positive terminal of which is' connected to the anodes 3, 4 through the choke coils 8 whose function is to oppose any changes in the currents flowing to the two anodes respectively. The eld coils 6 are connected across the anodes 3, 4 in series with a condenser 9. These field coils and condenser constitute an oscillating circuit such as that described in connection with Fig. 1 of my patents above referred to, except that the field coils 6 in the present arrangement are located lwith the axis vof the field in a vertical plane passing through both anodes, instead of'perpendicular to such a plane as they are in the case of Fig. 1 of the patents referred to. The axial field coil 5 Coils 8 operates the tube although it 'may properly be supplied by an external source.

The operation of the apparatus 1s as follows: Vhen no current is flowing through the oscillating circuit 6, 9, 6, lhecathode blast will be directed by the field of the coil 5 along the axis of the tube, passing midway between the anodes 3, 4, and the current through the tube will divide equally between the anodes. Any slight irregularity in the action of the tube, such as the shifting of the cathode blast caused by the dancing about of the pit in the surface of` the cathode from which it issues, will tend to make more current flow' through the anode 3, for example, than flows through the anode 4. The choke revent this momentary fluctuation from a ecting the whole circuit 2, 3, 8, 7 ,'5, and cause a momentary current impulse to flow through the oscillating circuit 6, 9, 6 from the anode 4 to the anode 3. This current the field coil 6 being wound in a suit.- able irection) will produce a magnetomotive force in the direction b (Fig. l), thus shifting the axial flux in the direction c, and deflecting thle blast toward the anode 3. This deflection of the blast still further increases the conductivity of the path 3 2, and diminishes that of the path 4, 2, t us causing a further increase in the current of the oscillating circuit from 4 to 3. When the condenser 9. has become charged to a certain point it causes the current in the oscillating circuit 6, 9, 6 to reverse, thus shifting the direction of the cathode blast toward the anode 4 and causing a still further increase of the current in the oscillatingy circuit in the negative direction. Thus the oscillations are sustained.

The relative strengths of the fields 5 and 6 should be so proportioned as to give the amount `of deflection to the blast which suits' crease in the strength of the field of the coil 6 inv order to produce the same deflection of the beam. The direction of winding of the field coil 5 is immaterial and the effect of concentrating and directing the cathode blast takes place satisfactorily with either a positive or negative field. When the field coil 5 is reversed, however, the connections of the coil 6 must also be reversed in order that the deflection of the blast may be in the evasae natin r field and for connecting the oscillating clrcuit with the apparatus may be employed, such as are illustrated in my patents above referred to. V

The theory of operation of the axial field is as follows: The discharge or current through the tube consists in a stream of negative electrons or corpuscles issuing from the cathode and another stream of positive electrons issuing from the anodes. The negative electrons, owing to their smaller mass and greater velocity, are peculiarly susceptibleL to the influence of the magnetic field, and it is on them that the effectiveness of this apparatus in the main depends. When one of these negative electrons is pro'ected from the cathode it finds itself urged 1n the direction of the anode by the electric potential-gradient in the tube, and in addition to thisit experiences a force due to the presence of the magnetic field. This force is perpendicular to the magnetic flux and to the direction of motion of the electron. If the electron happens to be moving in the direction of the magnetic flux it experiences no force from the 'magnetic eld. If on the other hand it is moving in a direction at right angles to the flux it will be continuously urged in a direction perpendicular to its motion, and hence, if the field is uniform, it will tend to describe a circular orbit whose radius depends upon the intensity of the field.- If the electron be projected in a direction oblique to the fiux the component of its motion parallel to the flux will be unaffected, while the component perpendicu- 'lar to. the flux will become a circle; and the resultant motion of the particle will be a helix having for its axis the direction of the magnetic field. If the magnetic field is an intense one the diameter of this helix will be small, and we may say with reasonable approximation to the 'truth that the particle follows the direction of the magnetic field. This approximation is the closer to the truth as the electric force urging the particle from the cathode to the anode is also nearly parallel to the magnetic flux.

In Fig. 3 a modified form of the apparatus is shown in which the continuous field coil 5 and the alternating field coil 6 are dispensed with and in their place are employed two oblique coils 10, 1l. These coils 10, 11 are connected between the junctions of the oscillating circuit with the power circuit and the two anodes respectively of the tube, so that they carry not only the alternating current of the oscillating circuit but also the continuous current of the power circuit. Their fields are therefore pulsating instead of alternating. Either of the coils 10, 1l acting alone will concentrate the cathode blast toward one of the anodes; when acting together they will concentrate the blast in an intermediate direction, depending on cvs-gene bthe relative strength of the currents in them.

The effect of this oblique field, whose direction changes .with the changes in the relative intensities of the currents in the two anodes, will be to excite oscillations in the manner described in connection -with Fi s. 1 and 2. As the points 12, 13 where t e power circuit is connected to the oscillating circuit are between the coils 10, 11 and the condenser 9, a considerable potential difference will occur at these points, usually much greater than that which exists between the anodes 3, 4. Hence, it will be necessary to make th'e choke coils 8 especially powerful to prevent large fluctuations in the power current. It is desirable to insert lan additional self-induction coil 14 in the oscillating circuit to reduce these potential differences as far as it is consistent with the relation of capacity to inductance demanded by the frequency desired and with the field intensit required to produce the commutar, the inductance coils, 8 may be made without iron and of comparatively small self-induction soas to invite the f'low of oscillations, and they will then constitute, with the condenser 9, a branch oscillating circuit 9, 12, 8, 8, 13. The natural frequency of such a complex oscillating system will, in general, be different from that which would be determined by the condenser 9 and the field coils 10, 11 alone.

It is not essential that the tube be provided with two separate anodes. Fig. 4 represents an arrangement having only one anode 4. In this case the oscillating circuit 4, 6, 9, 2 is connected between this anode and the cathode 2. The continuous field 5 alone will concentrate the cathodeblast upon the tip of the ano'd`4 as illustrated by the arrow a, while the effect ofthe alternating field 6 will be to produce a resultant flux whose axis shifts between'the positions indicated by the arrows c and c. The changes in resistance between the`r anode 4 andthe cathode 2 produced by the shifting of the concentrated cathode blast will sustain the oscillations in the oscillating circuit. This arrangement is analagous (except for the continuous field and the position of the valternating field coil 6) to that described in 'connection with Fig. 11 of my patents rey ferred to and is susceptible of various modi'- iications, such as its application `to two separate tubes as illustrated in Fig. 9 of those patents.

The concentration of the cathode blast by an axial magnetic field may be employed in arrangements inwhich changes in resista-nce of the gas column between the condition where the cathode blast. is concentrated and y, the condition where the discharge is allowed to take place without concentration, 'are relied upon to sustain the-oscillations in the oscillating circuit. In Fig.' 5 the field coil 15 when energized concentrates the cathode blast u on the anode 4. This coil is connected lietween the source of energy 7 and the anode 4, and the oscillatin circuit is connected across the tube throu this coil, so that the coil 15 is traversed y both the continuous power current and the alternating current of the oscillating circuit, whose resultant is a pulsatin current. The u1- sating .field thus pr uced has the e ect, at its maximum, o concentrating the cathode blast on the anode and inviting a still Greater flow of current through the tube from the oscillating circuit, and at .its mini- 'axis of the tube and producing when acting together 'an axial flux whichconcentrates the cathode blast upon the side of the'tube and away from the anode. The coil 16 is connected between the battery 7 and the anode 4, whilethe coil 17 is located in the oscillating circuit which is connected between the cathode 2 and the anode 4 in shunt to the battery 7, chokel coil 8 and field coil 16. When the oscillating circuit is discharging with the battery through the tube from 4 to 2 the two coils 16, 17 will neutralv ize each other and the resistance of the gas column in the tube will'be its normal resistance without concentration of the cathode blast. When the oscillatingl circuit discharges in the opposite direction the current in the coils 16 and 17 will act cumulativel'y to produce a magnetic field whose axis will be oblique to4 the-axis of the tube and will concentrate the cathode blast on the side of the tube as shown in Fig. 6, thus increasing the resistance of the gas column 4,

The utilization of the oscillator in conynection with an antenna'as a transmitter of wireless telegraph or telephone signals or for other purposes where a high frequency alternating current is desired, may be accomplished in any of the ways described in the patents referred to; one way of doing this is illustrated in Fig. 2 in which an additional oscillating circuit having condensers 18 and inductance 19 is employed. This circuit is coupled with the antenna 20 by a transformer 21, and the primary of the transformer, which is located in the oscillating circuit 18, 19, 18, is shunted by a key 22 by means of which the transformer primary can bev short-circuited. When the key 22 is open the oscillating circuit 18, 19, 18 is in tune with the oscillator and oscillates in synchronism therewith, but when4 the key su stantially as set forth.

22 is closed this additional oscillating circuit is thrown out of tune with the oscillator, and the transfer of energy to the antenna is interrupted.

Vhat I claim is:

1. An electrical oscillator wherein are combined an oscillating circuit, a Vacuum tube and means for producing an axial magnetic field for concentrating and directing the cathode blast, substantially as set forth.

2. 1n an electrical oscillator, the combination with a vacuum tube, of an oscillating circuit, means for producing an axial magnetic field for concentrating the cathode blast, and means controlled by the oscillat inv' circuit for shifting the axis of said field,

3,. In an electrical oscillator, the combination with a vacuum tube, of an oscillating circuit, means for roducing a continuous axial magnetic field) for concentrating the cathode blast, and an alternating or pulsating field controlled by the oscillating circuit and acting to shift the axisof the resultant field, substantially as set forth.

4. In an electrical oscillator, the combinathis 7th tion with a vacuum tube having two anodes I and one'cathode, of means for producing an axlal magnetic field for concentrating the cathode blast, and means controlled by the oscillating circuit for shifting the axis of said field so as to direct'the cathode blast alternately on the two anodes, substantially as set forth.

. 5. `In an electrical oscillator, the combination with a vacuum tube having two anodcs and one cathode, of an oscillating circuit, means for producing a continuous axial magnetic eld for concentrating the cathode blast, and an alternating field controlled by the oscillating circuit, laced at an angle to the constant field', ang acting to roduce a resultant magnetic field whose axls shifts from one anode to the other, substantially as set forth.

k'This s ecification signed and witnessed ay of December, 1906.

FREDERICK K.' VREELAND. 

